The aim of this proposal is to develop the next generation of miniature, high- density micro-stimulators suitable for chronic implantation in a patient's body to treat disorders of the peripheral nervous system. Maladies that could be treated in this way are problems with walking, such as after a stroke, and restoring natural sensations in a phantom limb after amputation. In this study, we will use custom-microfabricated electrode array structures to provide long-lasting neural interfaces. Custom packaging and assembly methods for the miniature implantable prostheses will also be developed. The tasks to be accomplished under this proposal include the fabrication of new electrode arrays for mating with pre- existing micro-neurostimulator designs. We will also evaluate the long-term biocompatibility and bio-stability of these implants through both in vitro experiments and animal surgical trials with active devices. Together with our vendors, we will thus build and test a new generation of high-density state-of-the-art peripheral neural stimulators. We will validate our designs in proof-of-concept animal implantation studies, and these will form the basis of an application to the FDA to do follow-on clinical work. The relationship between the proposed effort and the patient care mission of the VA is that these improvements are expected to open up new rehabilitative possibilities through more specific, targeted neural stimulation than has previously been possible. New devices for assistance with walking and restoring natural sensation in amputated limbs will be invented.